Solid-state transformations occurring in a weld are highly nonequilibrium in nature and differ distinctly from those experienced during casting, thermomechanical processing, and heat treatment. This article provides a description of the special factors affecting transformation behavior in a weldment. It reviews the heat-affected and fusion zones of single-pass and multi-pass weldments. The article also includes a discussion on the welds in alloy systems, such as stainless steels and aluminum-base, nickel-base, and titanium-base alloys.

This article discusses the various options for controlling fatigue and fractures in welded steel structures, with illustrations. It describes the factors that influence them the most. The article details some of the leading codes and standards for designing against failure mechanisms. Codes are presented for fitness-for-service and standards for fatigue and fracture control.

Corrosion of carbon steel weldments can be due to metallurgical effects, such as preferential corrosion of the heat-affected zone (HAZ) or weld metal, or it can be associated with geometrical aspects, such as stress concentration at the weld toe, or creation of crevices due to joint design. This article describes the issues related to corrosion of carbon steel weldments and the remedial measures that have proven to be successful in specific cases. It provides useful information on preferential HAZ corrosion, preferential weld metal corrosion, and galvanic corrosion.

This article reviews the metallurgical factors associated with welding. It provides a discussion on the preferential attack associated with weld metal precipitates in austenitic stainless steels. The article describes the corrosion associated with postweld and weld backing rings. The effects of gas-tungsten arc weld shielding gas composition and heat-tint oxides on corrosion resistance are also discussed. The article explains microbiological corrosion of butt welds in water tanks with the examples. In addition, it provides information on corrosion of ferritic stainless steel weldments and duplex stainless steel weldments.

Corrosion resistance can usually be maintained in the welded condition by balancing alloy compositions, shielding molten and hot metal surfaces, and choosing the proper welding parameters. This article describes some of the metallurgical factors that affect corrosion of weldments. It also reviews the considerations for selected nonferrous alloy systems such as aluminum, titanium, tantalum, and nickel.

This article provides a review of metallographic procedures and techniques for analyzing the microstructure of fusion welded joints. It discusses sample preparation, the use of backing plates, and common sectioning methods. It identifies the various types of defects that can occur in arc welded metals, organizing them according to the sectioning method by which they are observed. It describes the relationship between weld bead morphology and sectioning direction and its effect on measurement error. The article examines micrographs from stainless steel, aluminum, and titanium alloy joints, highlighting important details such as solidification and solid-state transformation structures and what they reveal about the welding process. Besides arc welding, it also discusses laser and electron beam welding methods, resistance and spot welding, and the welding of dissimilar metals.

Weldments exhibit special microstructural features that need to be recognized and understood in order to predict acceptable corrosion service life of welded structures. This article describes some of the general characteristics associated with the corrosion of weldments. It emphasizes the role of macrocompositional and microcompositional variations to bring out differences that need to be realized in comparing corrosion of weldments to that of wrought materials. The article concludes with a discussion on important welding practices used to minimize corrosion in weldments.

Solid-state transformations occurring in a weld are highly nonequilibrium in nature and differ distinctly from those experienced during casting, thermomechanical processing, and heat treatment. This article focuses on welding metallurgy of fusion welding of steels and highlights the fundamental principles that form the basis of many of the developments in steels and consumables for welding. Examples in the article are largely drawn from the well-known and relatively well-studied case of ferritic steel weldments to illustrate the special physical metallurgical considerations brought about by the weld thermal cycles and by the welding environment. The article provides information on welds in other alloy systems such as stainless steels and aluminum-base, nickel-base, and titanium-base alloys.